For checking or machining operations or repairs which must be carried out in inaccessible locations installations permitting these operations to be carried out at a distance are provided.
For example, in the case of pressurized water nuclear reactors, special equipment is available for carrying out checking operations inside the tubes or in the water container of the steam generators. In this case, intervention by an operator directly inside the water container must be avoided, since this part of steam generators is in contact, when the generator is in service, with the water of the primary circuit transporting radioactive elements, and remains itself radioactive.
Recourse has therefore been had to remote-control-led intervention devices which are more or less complex and which nonetheless require human interventions at the start or even in the course of operation.
Such devices generally include an installation designed to receive the tool or the checking or observation means which can be positioned beneath the tube plate of the steam generators, or the position of which can be modified with respect to the tube plate, by actuating these operations at a distance.
However, if the tool or the checking device placed in the receiver installation in operating position is to be replaced in the hostile environment, it is not possible, with currently known devices, to effect this operation at a distance. Instead, it is necessary to return the receiver installation, for the checking means or the tooling, into an accessible area in order to carry out the changing of the tool or of the checking means.
This operation must be carried out on equipment which has been in a radioactive environment, and on the other hand, the dismantling and reassembly operations of the equipment may be long and delicate.